Napoleon is known all over the world. Barry Edward O'Meara not so much.

Still, this Irish physician's friendship with the Emperor was such that Napoleon gifted him some personal effects – including his toothbrush and a pair of personalised snuffboxes. The items, along with a lancet used by O'Meara to bleed Napoleon, are found in a display case in a hallway of the Royal College of Physicians of Ireland (RCPI) on Kildare Street.

Details: 6 Kildare Street, rcpi.ie; open by appointment.

Camino Start Point

St James's Church

To modern pilgrims, the Camino de Santiago de Compostela begins in southern France or northern Spain and ends at the reputed burial site of St James in Galicia.

In Ireland, the traditional departure point on the Camino was St James's Gate, at the western entrance to Dublin. Pilgrims had their passports stamped here before setting sail for Spain and that tradition has never stopped. Camino passports can still be bought at St James's church. Outside, look out for the blue tile featuring a scallop – the emblem of St James. Inside, get your passport stamped.

Details: 01-453 1143; the sacristy opens 9am-12pm (Mon-Fri).

Freemasons' Hall

17 Molesworth Street

For a supposedly secret society, Freemasons' Hall is remarkably easy to access. Tours are conducted daily at 2.30pm in summer months, by appointment the rest of the year round, and cost €2 per person. What's more, there isn't a human lizard in sight.

What you'll see is a marvellous building steeped in symbolism. From dramatic set pieces such as the Grand Lodge Room to squares and compasses hiding in door knockers, seatbacks and lapel pins, every centimetre of Edward Holmes's Victorian design reflects its masonic purpose. The best thing, however, is the openness of the guides, who'll happily debunk any theories regarding the Illuminati or fake moon landings.

Father Pat Noise was a priest who died under suspicious circumstances when his carriage plunged into the Liffey on August 10, 1919.

Or was he? Certainly, the small bronze plaque embedded in the west side of O'Connell Bridge appears to commemorate a real man. But in fact, it was installed as a hoax. Snugly designed to fit a space once occupied by a control box for the ill-fated millennium clock, the plaque was fitted in broad daylight almost a decade ago. After several removals and replacements, it remains hidden in plain sight today.

Art or vandalism? You decide. The plaque itself states that it was "erected by the HSTI" – a playful anagram opening it up to all sorts of interpretation ...

Details: O'Connell Bridge (west side).

The Hungry Tree

King's Inns

The Hungry Tree greets walkers, barristers and benchers as they enter King's Inns' gardens from the south gate. It's a graphic spectacle: a bench being eaten alive by a London plane. And it's the cover image for 'Secret Dublin: An Unusual Guide'.

The bench dates from the early 19th century. Since it was installed, the tree has grown to engulf it – a slow-motion gastronomic exploit that has seen it listed as a heritage tree and "arboricultural curiosity" by the Tree Council of Ireland.

Details: kingsinns.ie; treecouncil.ie; gardens open daily.

Letterbox

Dame Lane

Roughly halfway down Dame Lane, you'll find an orange letterbox fixed to the wall. At first glance, it looks like an ... erm, letterbox.

In fact, it's a hidden gem of guerrilla art installed by artist Sarah Bracken. 'Letterbox Dublin' dates back to 2008, when Bracken labelled it with varying themes – 'Letters to God', 'Letter to the Past' or 'Confess Your Secrets'. When passers-by posted responses, she collected them to use as inspiration. The replies are brilliantly witty and weird, ranging from "I wish to win the lotto" to "I'm not really gay, but I do like to tease the boys".

Details: Dame Lane; brackensarah.com

Roof GardeN

Chester Beatty Library

Understandably for a city that's rained upon so often, Dublin doesn't really "do" roof gardens. That's not to say roof gardens are not "done", of course – as this peachy patch atop the Chester Beatty Library in Dublin Castle attests.

Split into different surfaces, the small space commands some stonking views over the Dubh Linn Gardens, and is freely accessible through the museum. Creative use of indigenous materials and timber trellises give both an Irish and a Japanese feel to it.

Throw in the museum itself, some amazing artefacts and a menu of Middle Eastern food at the Silk Road Café and you have the makings of a very interesting afternoon.

Details: cbl.ie; free.

Haughey's Honey Pot

Little Museum of Dublin

Seven years after Charles J Haughey died, and almost 22 years since he was Taoiseach, the Machiavellian prince of Irish politics continues to intrigue. As you read, 'Charlie', a mini-series starring Aidan Gillen and Tom Vaughan Lawlor of 'Love/Hate' is filming in Dublin. Sometimes, however, it's not the big books and TV series that get to the essence of a man. It's the smaller things, such as the inconspicuous-looking jar of Abbeville Honey hiding in The Little Museum of Dublin. Who knew Haughey was an avid beekeeper, or that he gifted his honey to family and friends "to keep them sweet", as the museum puts it?

Details: 01-661 1000; littlemuseum.ie; €5/€3.

Sweny's Chemist

1 Lincoln Place

Dating from 1847, this little pharmacy crops up in 'Ulysses' when Leopold Bloom calls for a prescription for his wife, Molly. "Chemists rarely move," he muses. "Their green and gold beacon jars too heavy to stir ... smell almost cure you like the dentist's doorbell."

Bloom buys a bar of lemon soap – something visitors can still do today from the drawers and mahogany shelves that James Joyce visited in 1904. What you can't do, however, is pick up a prescription. Sweny's closed as a chemist in 2009 and survives only thanks to a group of Joyce enthusiasts.

Details: 086 050 79995; sweny.ie; free.

The Ferocious Mingle Marcade

Camden Street

Step inside 60 Camden Street, Dublin 2, and you'll find Dublin's most vibrant exercise in Victoriana. The market arcade ("marcade", see?) is crammed not only with tasselled lamps, gramophones and cabaret curtains, but all manner of boutiques and businesses: a Thai nail salon here, a ribbon and lace shop there, even a medium telling fortunes.

At the heart of it all is an old-time silent cinema, with movies projected from a laptop while customers sip coffee from the nearby Oscar Verne's cafe, or gobble goodies from a host of other delis, pie-shops and eateries.

Details: theferociousminglemarcade. com; opens Thurs-Sun.

'Secret Dublin: An Unusual Guide' is published by Jonglez (€17.90) and is available now in all good bookshops, or online from amazon.co.uk